已知实数x满足x+1/x=3,则x^2+1/x^2-9=

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已知实数x满足x+1/x=3,则x^2+1/x^2-9=已知实数x满足x+1/x=3,则x^2+1/x^2-9=已知实数x满足x+1/x=3,则x^2+1/x^2-9=(x+1/x)=3两边平方得:x

已知实数x满足x+1/x=3,则x^2+1/x^2-9=
已知实数x满足x+1/x=3,则x^2+1/x^2-9=

已知实数x满足x+1/x=3,则x^2+1/x^2-9=
(x+1/x)=3
两边平方得:x^2+1/x^2=7
x^2+1/x^2-9= 7-9=-2